A method for providing partial color constancy of a stimulus represented by an array of picture elements each represented by a color spectrum. The method comprising: (a) assigning to each picture element in the array, for each color, a color value, thereby to provide a plurality of pre-processed single color images each respectively arranged as a series of pre-processed color values one at each picture element; (b) for each picture element, defining at least two regions of picture elements; (c) at each picture element, adapting each one of the pre-processed color values using pre-processed color values from at least one of the two regions of picture elements, thereby to form, at each picture element, a set of center response values; and (d) at each picture element, transforming the set of center response values into a set of center corrected color values, using response values from the two regions of picture elements to provide a plurality of processed single color images having partial color constancy.